This invention is for cutting or rolling asphalt or other surfaces, using a tool attached to excavating equipment such as a front-end loader, backhoe, or excavator. Each of these machines can have a bucket, to which the invention is attached.
The need for surface cutting and rolling tools arises during construction, when holes or ditches must be dug beneath existing surfaces. There are numerous methods for cutting through the surface so that it may be broken up and removed. One method is perforating the surface with power hammers. Another is the use of mobile cutting machines, such as asphalt saws, dedicated to this purpose, such as disclosed in U.S. Pat. No. 2,701,134. Similarly, for rolling smooth surfaces, machines dedicated to that purpose have been used. A disadvantage of these methods is that special equipment must be brought to the site that might not otherwise be required there.
A common method, which is the method used with this invention, is the use of cutting or rolling tools, which can be attached to mobile equipment already in use at the job site. Such equipment frequently includes graders, bulldozers, backhoes, front-end loaders, and other excavating equipment. These machines may have buckets, boards, or blades, to which the tool is attached, and thereby is driven. As the driving equipment moves forward and downward force is applied, the tool cuts or rolls the surface. Desired features of such attachments are that they be easily attached and detached, and while attached, maintain a stable and rigid connection to the driving equipment. The tool should not twist from side to side, or up and down with respect to the ground, as it is being advanced across or through the surface.
A common means for attachment uses the concept of a C-clamp, which fits over one wall of the bucket. A C-clamp type mechanism was used in a roller attachment manufactured in the 1960's. C-clamp mechanisms have also been used in several asphalt cutter devices. U.S. Pat. No. 3,743,358 to Guest uses this concept. Subsequent inventions, disclosed in U.S. Pat. No. 4,076,314 to Dodich, and U.S. Pat. No. 4,420,189 to von Ruden, modify the C-clamp.
Typically, buckets used with excavator equipment depend on a reinforced lip for strength. This lip consists of a strip of metal at the leading edge of the underside of the bucket. Relative to the lip, the bucket walls are easily deformed. If a bucket has been deformed, a problem with prior devices is that they do not successfully accommodate the deformation and provide stability while the device is in use. Because a large flat area of contact will tend to permit a distorted bucket to shift, many of the prior devices rely on discrete points of contact. Yet because of the relative thinness of the bucket walls, these points must be at the lip of the bucket, which does little to stabilize the tool during use.
Another feature of using tools attached to excavating equipment is that when these tools are driven to cut or roll surfaces, large forces are applied by the equipment through the tool to produce penetration or smoothing of the surface. This causes problems with prior attachment mechanisms, which have a limited area of contact between the roller or cutter tool and the bucket. The combination of the large forces and limited contact area increases the likelihood that the bucket will be punctured or bent. This is true of the C-clamp devices, in which contact with the bucket is limited to several discrete points, such as the ends of clamping screws and the forward edges of a C-clamp within a limited area at the lip of the bucket. Again, this configuration does little to promote stability. Additionally, the pressure of the bucket lip against the bearing end of the C-clamp will cause the metal there to fail. Deformation occurs, reducing the desired clamping action.
Alternatives to the use of a C-clamp have been attempted. In U.S. Pat. No. 4,331,362, an asphalt cutter is clamped to the bucket by means of a V-shaped mounting bracket. The bottom of the bracket receives the force from the bucket; thus this device does not overcome the problem of undue stress on the bucket lip. Furthermore, a bucket whose walls have become distorted and are no longer flat will tend to shift.
In light of these problems associated with using tools attached to excavating equipment buckets, the ideal attachment device should balance the needs for stability, the need to accommodate deformed buckets, and the need to protect the bucket walls. Accordingly, as explained below, this device described herein is designed to have zones of contact that are sufficiently spaced to provide stability, sufficiently large to discourage puncturing, and sufficiently discrete to accommodate deformities in the bucket. Furthermore, the device is designed to encourage transmission of forces to the frame instead of to the clamping mechanism, thereby reducing stress on the clamping mechanism.